Yesterday evening, too bored by what TV was proposing to me, I decided to watch a conference of Mathias Fink, a french researcher working on multidisciplinary application of waves. Specially shear waves. Here is a brief summary of his talk.
In solids, waves have two principal components: compression waves (P-waves for primary) moving in the direction of propagation, and shear waves (S-waves, for secondary) that make ripples in the plane orthogonal to that direction. Since compression waves propagate in the direction of propagation, they move faster than shear waves.
Usually ultrasound equipment in medicine only use compressional waves. But since human tissues have a high bulk modulus, the P-wave speed is relatively constant (around 1580 m/s). Human tissues are very stiff if you apply isotropic constraints on them (like pressure of water). However M. Fink and his colleagues proposed a new way to investigate human tissues by first sending a strong compressional wave in the tissue that is able to make ripples in the body, then shear wave are produced and they can be used for imaging fine structure, since the shear modulus depends very strongly on their composition. For instance tumor have a much higher shear modulus than healthy tissues.
That idea finally allows to really see seismic waves inside the human body, producing something like 5000 images per second ! Heart beat for instance produce such seismic waves. From those ideas, some former colleagues of Fink created a company, Aixplorer, aiming at beating big companies on the body imaging ground (Siemens, Philips, and General Electric)
Last but not least, Fink is presently investigating if whether or not nerve cell may act as piezzo-tranducers, meaning that electric signal and mechanical stimulus may be linked in the brain. Nerves could possibly respond to some mechanical pinch or may be mechanical waves. A new way for telepathy ?
In solids, waves have two principal components: compression waves (P-waves for primary) moving in the direction of propagation, and shear waves (S-waves, for secondary) that make ripples in the plane orthogonal to that direction. Since compression waves propagate in the direction of propagation, they move faster than shear waves.
Usually ultrasound equipment in medicine only use compressional waves. But since human tissues have a high bulk modulus, the P-wave speed is relatively constant (around 1580 m/s). Human tissues are very stiff if you apply isotropic constraints on them (like pressure of water). However M. Fink and his colleagues proposed a new way to investigate human tissues by first sending a strong compressional wave in the tissue that is able to make ripples in the body, then shear wave are produced and they can be used for imaging fine structure, since the shear modulus depends very strongly on their composition. For instance tumor have a much higher shear modulus than healthy tissues.
That idea finally allows to really see seismic waves inside the human body, producing something like 5000 images per second ! Heart beat for instance produce such seismic waves. From those ideas, some former colleagues of Fink created a company, Aixplorer, aiming at beating big companies on the body imaging ground (Siemens, Philips, and General Electric)
Last but not least, Fink is presently investigating if whether or not nerve cell may act as piezzo-tranducers, meaning that electric signal and mechanical stimulus may be linked in the brain. Nerves could possibly respond to some mechanical pinch or may be mechanical waves. A new way for telepathy ?
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